Acoustic panelling



March l, 1960 J. FISCHER ACOUSTIC PANELLING Filed Jan. 17, 1956 /N Ven for dea/1 Tischer 2 BX @ww United States Patent O ACOUSTIC PANELLINGV Jean Fischer, Skt. Clemens, Denmark Application January 17, 19156, Serial No. 559,722 Claims priority, application Denmark April 16, 1955 3 Claims. (CI. 181-33) .Mounting of acoustic panelling on one or more of` the bonding surfaces of a room isemployed to a large extent for regulating the acoustic conditions in living rooms, meeting halls, and work-rooms for the purpose of reducing reverberation time and lowering the noise level.

In a widely used panelling of this type, the surface facing the room consists of parallel lists mounted in parallel spaced relationship with slot-shaped interstices, sound-quenching material being provided behind said lists, if necessary in combustion with continuous or cellular cavities.

The generally used embodiments of such` acoustic panellings suffer from several drawbacks. Thus, the mounting of the panelling involves rather troublesome labor involving much time and money, and after having been mounted the panelling cannot in practice be dismounted and mounted anew without being destroyed, so that inspection and replacement of technical installations, such as wirings, covered by the panelling is greatly impeded and increased in cost. Further, soon after the mounting of such a panelling upon a ceiling small particles of the sound-quenchingmaterial will according to experience sprinkle from the ceiling due to shocks and.r

vibrations in the building, these particles falling through the slots of the panelling lists. In order to eliminate this inconvenience it has `been suggested to close the slots by means of a layer of paper immediately above the lists secured to the ceiling as by nailing, but it proves in practice that such obstruction layer considerably reduces the acoustic effect of the panelling by reducing the total quenchingI or damping effect and shifting the maxiinum` point thereof away from the frequency regions within which the damping is particularly desirable. It is also known to use listswhch are of channel formation and are placed with their back against the room` A sound-quenching material contained in the channel or cavity of the lists will thus be prevented from sprinkling through the slots, but this arrangement involves restriction of possible variations with respect to the acoustic function and does not facilitatethe mounting and dismountin-g of the panelling.

An` object of the prese-nt invention is to eliminate the drawbacks and disadvantages pointed out in the foregoing. Thus the invention relates to an acoustic panelling of the type comprising a plurality of parallel lists covering some sound-quenching material, said lists being of channel formation and being laced with slot-shaped interstices and with their open` side turned away `from the room, and according to the invention each list comprises a laterally projecting flange extending across the slot-shaped interstice to an adjacent list and thus forming a bottom in the slot between a pair of adjacent lists. In

this way sprinkling of dust through the slot shaped interstices is totally prevented and, at the same time, the laterallyprojecting ange constitutes a convenient means fo-r securing the lists in such a way that they can readilyv be mounted and dsmounted again and again, as'will be more:` fully explained in the following description.

The desired acoustic elfcctneccssitates some communi.. cation between the room space and thespace or cavity behind the lists. In a preferred embodiment of. the invention such communication is established in the way that the wall of the channel lists carrying said flange is -somewhat higher than the opposite wall of the lists.

Hereby a slit is provided adjacent the bottom of the slot between a pair of lists, said slit extending through` one bounding wall of the slot and communicating with; the channels or cavities of the lists which, if desired, may further communicate with a greater continuous or cellular cavity between the lists and the surface on whichY they are mounted.

In this embodiment the cavities of the channel lists may, `according to the invention wholly or partly belong to the resonance space of the acoustic damping system.' However, the communication with the cavity or system of cavities behind the lists may also be provided in0 other ways. Thus, in another embodiment of the invention the channel-shaped lists are perforated on the sur faces facing the room and/or the slots, said perforations being preferably covered by a foil, for example a layer of tissue paper, placed inside the lists. It has appeared, that such` covering of the perforations does not detrimentally inuence the general acoustic effect or cause a.

prises slot-shaped interstices between a plurality of lists.I

and cavities containing sound-quenching material behind said lists. n

A panelling in `accordance with the invention offerti panel` or surface absorbency as well as resonance ab sorbency, porosity absorbency, and slotcavityabsorbency, so that by proper correlation of the mutual elfect` of these four diiferent forms of` absorption it is possible to provide practically speaking any desired amount. and frequency characteristic of damping,

The lists may expediently consist of metal of a suit?` able thickness and rigidity, bent or extruded into the desired channel-shape, e.g. aluminium sheet of a thicknessM of about 1- mm. or thin iron sheet of a thickness of about 3A mm. Other materials may, however, also be taken.

' into consideration, e.g. suitable plastics with or without.

reinforcements and with the desired cross section provided by extrusion or pressing.

ln all cases, the comparatively small thickness of material and the stability as t`o shape and size of the materials used will allow the use4 of a mounting system' based on easily releasable clips or clamps which permit the dismounting` and re-mounting of optional sections` of an acoustic panelling according to the invention,

thereby giving easy access to technical installations lo* cated behind the said panelling;

In a preferred embodiment of thel invention thelist'sf are secured to` carrying rails mounted upon the surface to be covered by the panelling, said securing` being* established by` means of said laterally projecting flange Fig, 4 a carrying clip,

Fig. `5` part of a panelling list, p l.- Fig. 6 a section online VI-VI of Fig. 7 of another embodiment' of the g invention,

Fig. 7 a section on line VII-VII" of Fig. 6, and j Fig; 8 a` transverse section of a modified panel list?Y n the drawing, 1 designates part of a bounding surface, here a ceiling, in a room not further shown, carrying a base composed of bars 2 of metal or plastic and `with a U-shaped cross section .secured to the ceiling 1 by suitable means, not shown, e.g. screws, bolts, or nails. SuchI bars 2 must be supposed mounted evenly distributed over the whole part of the ceiling to be pro-` vided with acoustic panelling and with a suitable spacing o'f e.g. about 1 m.

The U-shaped bars 2 are vin their backs provided with retaining members 12 with a spacing corresponding to the pitch in the list surf-ace,'facing the room, of the finished acoustic panelling, and consisting of resilient tongues which may be produced by stamping and bending outwards of the material of the bar 2 if the said material'is suited therefor. If this is not the case, the retaining members, 12 may be produced separately and subsequently mounted on or cast into the' bars 2. Y y The bars 2 carry by means of the retaining members 12 directly or indirectly a panelling of parallel elongated members or lists 3, each of which is made as an upwardly open chan-nel of a substantially rectangular cross section with a substantially ilat bottom wall 3a and mounted with slot-shaped interstices 6 extending substantially perpendicular to the direction of the bars 2.

vIn the embodiment shown in Figs. 1-5 the lists 3 are secured to the bars 2 by means of hook means composed `of resilient clips 8 provided with a hole 9 for co-operating with the .retaining members 12 and with a bent-over end 10 which acts as clamp and cooperates with an outwards-bent flange 4 along one side edge or wall 3b of the associated list 3, while the otherv e'nd 11 is bent downwards and engages under an inwardly-bent Harige 5 at the opposite side wall 3c of the list 3.' lThis side edge or wall of the list is somewhat lower, so that the slot 6 between two adjacent lists, as shown in Fig. l, is covered by the ange, but opens laterally over the ange 5 into the cavity inside the list 3, thus placing the slots in communication with the space within and behind the lists.

Flange 4 and clip portion 10 have cooperating, interlocking rib and groove means 14, 15 for resiliently res'isting movement of the flange laterally outward relative to the hook means.

This space may be completely lled with porous sound-quenching material, but a more favourable damping effect is as a rule obtained if this total space is only partly filled with sound-quenching material and otherwise serves as a continuous resonance cavity or several separated resonance cavities. This may in practice be carried out in many different ways, a few of which are illustrated as mer: examples in Fig. 1.

Thus, asingle strip of the sound-quenching material 7 may" be placed in each of the channel-shaped lists completely or partly iiiling out the channel-shaped cavity of the lists and extending more or less upwardly between the U-sha'ped carrying bars 2.

- In a variation of this embodiment, shown as number two from the right in Fig. 1, the sound-quenching material is provided in the form of thinner strips which cover the bottom of the channel-shaped cavities of the lists, but leaves a passage free from the slot 6 upwards into a continuous cavity between the carrying bars 2.

A third embodiment, shown as number three from the right in Fig. l, is related to both of the latter, the sound-quenching material here extending upwards between the carrying bars 2 into complete or approximate contact with the ceiling surface 1, but being at the same time so cut off that free passageis leftJfrom the slot 6 to the cavities bounded thereby between the carrying bars 2.v

Finally', Fig. 1 to the far left shows an embodiment where thesound-quenching materialr is only provided outsidethe lists 3 and is secured to the ceiling surface $4,928,745Y A Y, -s y.

4 1 proper, so that the cavities of the lists are completely incorporated in the construction as resonance cavities.

In all the embodiments shown the lists may as mentioned in the foregoing be more or less perforated, and the features illustrated by the different embodiments shown may be combined in any desired manner.

The embodiments of the members shown in Figs. l-5 serving for securing the lists to the carrying bars 2 should be regarded only as illustrating examples which can be varied in numerous days dependent on the design of the lists and the part they are intended for playing in the acoustic damping system. It is, for example, possible to secure the lists 3 direct to the carrying bars 2 as illustrated in Figs. 6 and 7, in which ange 4 of channel 3 is engagedv by retainers 12. 1

The necessary communication from the slots to the remaining acoustically active cavities of the construction Tmay be provided by way of perforations in the side walls of the slots or in the covering ange or in both places. The surface of the lists facing the room may be proled in any desired manner determined out of regard to the attainment of a suitable sound absorption in combination with an attractive appearance and ease of manufacturing and shipping the lists. Thus, Fig. S

iilustrates a list having a more shallow cross section than that disclosed in Figs. 6 and 7. The slot between two adjacent lists of the type shown in Fig. 8 has across, section tapering in the upwards direction, but no detri" mental effect is caused by this shape which, apparently, makes possible a very compact .packing of a number of lists.

The present acoustic panelling may also be used in combination with or as a component of plants for heating, Ventilating, or air-conditioning the particular room. in this case the slot-shaped interstices between the lists communicate with cavities located behind the lists, which cavities are in turn in communication with channels or ducts through which air is exhausted or introduced. Due to the fact that the slots extend over the full area ot' the acoustic panelling and to their considerable size relative to the total area of the panelling there may by this Varrangement Ibe exchanged very large quantities of air per time unit without it being necessary to use sohigh ow rates as to entail the risk of draught and noise.

l claim:

l. An acoustic `covering, for rooms, comprising a base, hook means carried by said base, a plurality of parallel elongated members, each of which is of channel formation and comprises a substantially at bottom Wall spaced from said base and two side walls extending from said bottom wall towards said base, said elongated members being spaced from each other upon said base so as to form slots between the opposed side Walls of adjacent members, one of said sidewalls of each elongated member being provided at its edge remote from said bottom wall with a lateral flange extending completely across the adjacent slot, said second wall having an inwardly turned flange at its free edge, the bottom wall being spaced from the base by a distance substantially greater than the height of the hook means and the space between said bottom wall and the flange on the second wall being substantially greater than the thickness of that portion of the hook means beneath which the inwardly turned flange is engaged, and sound quenching material within said channel members, both said flanges .being engaged beneath said hook means to secure the elongated mem bers to the base along both their edges.

2. In a covering as claimed `in claim l, cooperating rib and groove means on said hook means and on one of said flanges for resisting movement of said ange laterally outwardly relative to the hook means.

3. In a covering as claimed in claim l, the inner face of the ange ou the second wall being spaced outwardly.

from the outer face of the ange on the rst wall so as to provide la slot therebetween.

References Cited in the le of this patent UNITED STATES PATENTS Barnett Oct. 6, 1931 Valenti l June 7, 1938 

